Helicopters can come under enemy fire in conflict situations. This enemy fire may include small arms fire and heavy machine gun fire.
If a helicopter pilot was aware that the helicopter was under enemy fire, evasive action could be taken. This may break the lock the enemy has on the helicopter, which would minimise damage to the aircraft structure and safeguard personnel.
Thus it is desirable to detect incoming enemy fire, from small arms fire up to heavy machine gun fire. It would also be desirable to determine the direction of the incoming enemy fire. For example, information related to the direction of incoming enemy fire could be used to prevent the helicopter turning into the enemy fire, or to identify the location of the enemy e.g. by incorporating it with information about the local terrain.